Surface Finishing Technologysince 2009
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Process flow of powder coating.
Part preparation or the pre-treatmentremove the oil,dusty,rust from the surface of workpiece, and creat the layer of resistant to corrosion increase the adhesion force "phosphate coating"
Chemical pre-treatments involve the use of phoshpates or chromates in submersion or spray application. The pre-treatment process both cleans and improves bonding of the powder to the metal.
The powder application
The most common way of applying the powder coating to metal objects is to spray the powder using an electrostatic gun, or corona gun. The imparts a positive electric charge to the powder, which is then sprayed towards the grounded object by mechanical or compressed air spraying and then accelerated toward the workpece by the powerful electrostatic charge.
When a thermoset powder is exposed to elevated temperature, it begins to melt, flows out, and then chemically reacts to form a higher molecular weight polymer in a network-like structure. This cure process, called crosslinking, requires a certain temperature for a certain length of time in order to reach full cure and establish the full film properties for which the material was designed. Normally the powders cure at 180-200 for 15 minutes. The application of energy to the product to be cured can be accomplished by convection cure ovens, infrared cure ovens, gas fired ovens, electric oven.